The present invention relates generally to antenna systems, and more particularly, to an antenna system and improved antenna support structure for use on a spacecraft.
Antenna systems used on spacecraft employ an antenna support structure to secure them to a spacecraft and deploy an antenna once the spacecraft is in orbit. Conventional antenna support structures have not had suitable profiles that allow antenna nesting (stacking) when they are disposed within available launch vehicle fairings. Also, conventional antenna support structures have not been readily adaptable to support different antenna dishes without the requirement of substantial additional analysis. Furthermore, conventional antenna support structures are not easily changed to allow support of different antenna dishes.
It is therefore an objective of the present invention to provide for an antenna system and improved antenna support structure for use on a spacecraft.
The present invention provides for an antenna system and improved antenna support structure that is preferably used on a spacecraft. An exemplary antenna system comprises an antenna dish, an antenna positioning mechanism, and the antenna support structure coupled between the antenna dish and antenna positioning mechanism. The antenna support structure preferably comprises a composite ring attached to a rear surface of the antenna dish and a boom structure coupled to the composite ring and to the antenna positioning mechanism. The boom structure preferably comprises a plurality of tubular fingers that interconnect the composite ring and the antenna positioning mechanism. The plurality of tubular fingers meet at a common element (or meet forming one element). The boom structure may further comprise one or more lateral supports that interconnect the plurality of tubular fingers.
The composite ring is preferably disposed in a plane containing the center of gravity of the antenna dish. The composite ring, tubular fingers, and lateral supports preferably comprise graphite fibers. The composite ring, tubular fingers, and lateral supports may have rectangular or circular cross sections.
The present invention is directed toward reducing mass, enhancing stiffness, creating a shallower antenna system profile, and providing a structural configuration for the antenna support structure that is adaptable to change. The present antenna support structure has a shallower profile that expedites antenna nesting (stacking) while fitting within available launch vehicle fairings. The structural configuration of the antenna support structure is such that elements may be added or subtracted to accommodate various antenna dishes without substantial additional analysis.
Critical advantages of the antenna support structure are that torsion on the antenna about an axis that is parallel to the support system is converted to and resisted, primarily, by bending in the support boom. In addition, loads transferred through the xe2x80x9cringxe2x80x9d, attached to the antenna dish, are distributed to multiple connection points in the boom allowing for a smaller ring cross section than conventional backup structures.
Bending within the fingers of the boom structure is preferred over pure torsion because bending is resisted better than torsion in composite systems. The ring is preferably attached to the antenna dish in the same plane as its center of mass. This reduces eccentricity of the antenna mass with respect to the boom, lowering torsion on antenna support structure during launch of the spacecraft.